1. Field of the Invention
This invention relates to methods of correcting for aberrations in an optical system, more specifically through the use and placement of media at appropriate positions in an optical system, the properties of the media being such that the refraction of the media can be modified by exposure of the media to light.
2. Background Information
Adaptive optical systems have been employed by astronomers, optical engineers, and vision scientists to compensate for wavefront aberrations generated by the atmosphere, telescope optics, optical design errors, and the inherent wavefront errors of the human visual system. In these systems, a wavefront sensor is used to measure the aberrations from the target to the imaging sensor. A computer is used to calculate the conjugate to the measured aberrations and deform a mirror with actuators to place the conjugate aberration on the deformable mirror's surface. The deformable mirror (DM) is usually placed at the image of the pupil to minimize isoplanatic errors in the optical system. When the DM is not placed at the pupil or an image of the pupil, the angular field of view, which the aberrations are corrected over, will not be as large.
To correct optical system aberrations, opticians will polish compensating surfaces on one of the elements. As an example, conjugate errors are often polished into the secondary mirror of a two-mirror telescope to compensate for errors in the primary mirror. This process can take hours in a production shop and days in a precision optical fabrication facility. As another example, the spherical aberrations present in typical camera systems are removed by polishing an aspheric surface onto one of the lens surfaces. Thus, fabricating an aberration conjugator as such is known and has been used in a number of applications.
In addition to adaptive optics and optical polishing, other approaches address the correction of aberrations in optical systems. These include ion polishing, the deposition of thin films, the use of binary optics, holographic elements, real time holography, and spatial light modulators.
All of these approaches have drawbacks. For example ion polishing and thin film deposition must be performed in a vacuum. Virtually all of these methods are costly and time consuming Some are disadvantageous because of low efficiencies or because polarized light must be used. A less labor intensive, cost effective, and faster method of correcting aberrations in optical systems would provide significant advantages.